Effects of ocean acidification on statolith calcification and prey capture in early life cuttlefish, Sepia officinalis

The inﬂuence of elevated seawater pCO2 on statolith calciﬁcation and prey capture was investigated in the early life stages of the common cuttleﬁsh, Sepia ofﬁcinalis. Cuttleﬁsh were reared at 15°C and 35 psu in a ﬂow-through seawater system under three pCO2 conditions, 700 µatm (control), 1400 µatm , and 4000 µatm during 63 days in June to August 2009. Both, embryonic and hatchling cuttleﬁsh raised under 4000 µatm showed signiﬁcantly reduced statolith calciﬁcation, whereas those grown under control and 1400 µatm did not. Reduced calciﬁcation was demonstrated by comparing 18 transects characterizing the anterior surface of the statoliths. The statolith morphometrics that showed the most remarkable changes between the different pCO2 conditions were total statolith length, rostrum transects, wing area and statolith weight. Statolith microstructure was signiﬁcantly affected by irregularly arranged statoconia, which were typical in the statolith wing area, replacing the highly compact and well-arranged crystals in normal growing statoliths. This abnormal crystal structure can have profound effects on statolith density and consequently on its normal functioning as a tool for buoyancy, acceleration and movement. Changes in statolith morphology and microstructure may inﬂuence the prey capture efﬁciency of the early life cuttleﬁsh. At 4000 µatm they showed a reduced ability to capture prey and were not able to successfully launch attacks against prey organisms. In order to verify these observations, a second experiment was conducted over 85 days in May to August 2010. Preliminary results showed that statolith morphology and microstructure differed again in the 4000 µatm group. On the other hand, prey capture ability of the hatchlings showed recovery during the experiment, indicating a possible acclimation.